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E. I). LEE.

IGNITION COIL.

APPLICATION FILED IuLY 2s. IQII.

ateuted June 24, 1919.

FII g UNITED sTATEs PATENT oEEIoE.

EARLE r. LEE, OF ROCHESTER, NEWYORE, Assia-NOR To NORTH EAST ELECTRIC COMPANY, OE ROCHESTER, NEW YORK, A CORPORATION OE NEW YORK.

IGNITION-COIL.

T0 all 'whom it may concern:

Be it known that I, EARLE P.l LEE, a citizen of the United States, residing at Rochester, in the County of Monroe and State of New York, have invented certa-in new and useful Improvements in Ignition-Coils; and I do hereby jdeclare the following be a full, clear, and exact description ofthe invention, such vas .will enable others skilled in the art to which it appertains to make and use the same.' 'K

This invention i relates to an inductioncoil suitable foruse in `producingthe hightension discharge used for ignition in internal-combustion engines.' y y Coils for the purpose in question are usually made with long stra-ight cores of iron,

upon which the primary and secondary windings are arranged concentrica1ly,the primary winding beinguniversally arranged within the secondary winding.

The arrangement of the windings as just described vhas been thought to be essential, owing partly to the requirements of thorough insulationj of the secondary winding, and also' to the fact that a primary winding located at any substantial distance from a core of the kind in question does not eiiectively magnetize the core, because of the large amount of magnetic leakagey which takes place between the ends thereotI within the space betweenthe core andv the'winding.

Where an ignition-coilis energized by a constantsou-rceof `current such as a secondary battery, the flow of current through the primary winding `during normaloperation of the apparatus is comparatively small, owing to the fact that it is interrupted at short intervals and-is' considerably reducedl by inductance in the coil. In such an apparatus,

however, if the coil remains in connection with the battery while the apparatus is not in operation, so that the primary winding is subjected continuously to the full E. M. F. of the battery, a much greater flow of current occurs, with a resultant heating eiect in the coil which is liable to damage or destroy the coil. For this reason it is common to employ resistance-devices, automatic cut-outs and the like to avoid the danger of such a circuit-closure occurring while the Specification of Letters-Patent.

- terial.

Patented June 24 1919.

Application filed July 23, 1917. Serial No. 182,302.

tinuous heavy flow of current through the primary winding, so that the use, with such a coil, .of external resistance-devices, automatic cut-outs and the like may be dispensed with. To this end it is proposed to reverse the usual arrangement of the primary and secondary windings, the secondary winding being placed next to the core, while the pri-- mary` winding isarranged outside of the secondary winding so that it ,may be fully eX- posed to thecooling ell'ect of the atmosphere or of adjacent bodies of heat-conductive ma- In this way the coil is adapted to dissipate a comparatively `large amount of energy in the form of heat without attaining a temperature which will be injurious to its structure.

The problem of suitably insulating ay secondary winding arranged within a. primary windinghas been solved bythe arrangement of parts hereinafter described,'while it has ybeen found that, by the .use of fa magnetic circuit ofy vsuitable, character, y,the arrangement of the windings characteristic of the presen-t invention may be. employed without loss of eiiiciency' in the coil, the essential point in this respect beingthe use of va kmagnetic Icircuit such that the lines-[of force eX- ternal to the Acentral core-member pass ou-tside ofthe-primary,winding, and not between vthis fwinding. and the central coremember. Y i,

Anotherobject of the invention is to provide a simple and etlectivemeans forgrounding one .terminal of the secondary winding of the/coil. To this end it is proposed to employ 'means `including a `pin which isl thrust7 into the central 4core-memberI between the iron wires of whichthis member is composed." y 1 A third objecty of the invention is to counteract the 'condenser effect which tends to occur between the primary and the secondary windings of the coil. To this end it is proposed to interconnect theprimary and secondary rwindings through an air-gap, which is of suiicient length to prevent the flow of primary current, while short enough to prevent the accumulation of a `static charge vof any substantialtension in the primary and secondary windings. Y

. The invention will be more fully set forth in the followingdescription of the apparatus illustrated in the accompanying drawings, in which Figure 1 is a plan-view of an ignisistingof parallel iron wires. Since the inl verted arrangement of the windings characteristic of the present inventionmakes neeessary a magnetic circuit of low reluctance, in order to secureA a high degree of efficiency, the core-member 10 is combined with a yokemember 11 in the form of a square ring, composed of iron wire wound continuously. This wire coil is held in suitable form at 'the corners by means of sheet-metal clips 12. The lower end of the core-member 10 is in direct engagement with the yoke-member, but as a slight air-gap in the magnetic circuit has been found to be desirable, a spacer 13 of insulating-material is interposed between the yoke-member and the core at the upper end of the latter.

The core is surrounded by a sleeve 14 of insulating-material, and upon this sleeve the secondary winding 15 is mounted directly. The successive layers of this winding are insulated from each other in the usual manner. The secondary winding is inclosed by three concentric sleeves of insulating-material 16,

- 17 and 18 respectively. The sleeves 17 and 18 are continuous, as shown in Fig. 3, while the sleeve 17 is interrupted at one point to produce a longitudinal slot 21.

The primary winding 19 is wound upon the sleeve 18. In order to insulate the secL ondary winding thoroughly from the yokemember 11, caps 2O of insulating-material are placed upon the ends of the coil, and the primary winding is wound from edge to edge of these caps, as shown in Fig. 2, being thus securely retained in place at its upper and lower extremities. The slot 21 is formed for the purpose of receiving the outer terminal of the secondary winding, this ,being the terminal which is connected with the sparkplugs of the engine. This terminal22 extends upwardly through the slot 21, and is incloscd in a tube 23 of insulating material extending for some distance above theupper end of the coil. The terminal 22 is thusinsulated from the primary winding by the combined thicknesses of the tube 23 and the sleeve 18. 4

Owing to the substantially closed magnetic circuit of the coil the casing` in which it is inclosed may be made of metal, which has, among other advantages, that of readily carrying ofiI heat generated in the coil. As illustrated the casing 24 is in the form of a casting with an open top, which is covered by a cap 25 of molded insulating material. The various parts of the coilare held in their proper relative positions by means of a tie-rod 26, which passes axially through the central core-member 10. A plate 26 screwed to the lower end of the tie-rod bears against the bottom of the yoke-member 11, while a plate 28 anda nut 29, near the upper end of the rod, engage the upper surface of the yoke-member, thus holding the central coremember and the yoke-member rsecurely in proper relation to each other. "The lower end of the tie-rod passes through the bottom of the casing and is fixed by a nut 30, while the upper end passes through the cap 25, which latter is secured in place by a nut 31 on the end of the rod. f y

The cap is provided with a depending portion 32 perforated to receive 'the terminal 22 and its sheath, and a metallic insert 33 partially embedded in the cap constitutes a binding-post, being threaded to receive a nut 34 by which a high-tension conductor may be attached to the binding-post in the usual manner. As a convenient method of assembling the parts the binding post may be longitudinally perforated for the introduction of the terminal-wire 22, and after the cap 25 has been xed in place the upper extremity of the terminal-wire may be soldered in place in a recess at the upper end of the binding-post. The downward projection 32 increases the air-space and the surfacewhich must be traversed by a high-tension dischargein passing from theterminal-wire to any adjacent metal part.

The primary terminals of the coil are attached to external conductors through binding-posts 35, molded in the cap 25, the terminal wires 36 being soldered, or otherwise secured, to these posts. The primary terminal-wires pass outwardly through channels formed in the insulating sleeve 17,` and through perforations in the upper `cap 20, as shown in Fig. 2.

The inner terminal of the secondary winding is grounded as usual, and a Vfeature of the invention resides in the simple and effective means employed for this purpose. A strip 37 of sheet-metal passes from the inner terminal of the winding` to the lower end 0f the insulating sleeve 37,;1nd is bent inwardly against the lower end of the coremember 10. A pin 38 is then driven through a hole in the sheet-metal, and into the core between the wires thereof. For additional security the head of the pin may be soldered to the strip 37. vThe forcible engagement of the pin with the iron wires insures a reliable metallic contact. The iron wires of the core are `also in conductive engagement with the tie-rod 26, while the latter` is in conductive engagement with the metal casing 24. The casing 24 isshown as provided with an integral flange 39 by which it may be secured in place upon any convenient part of the structure of the engine with which the ignition apparatus is employed, and in this way a metallic conductive path or ground for the secondary current is provided through the pin 38, the core, the tie-rod 26 and the casing to the engine and thence to the spark-plugs.

It has been found that when an ignitioncoil is in operation an effect is produced in the coil similar to that of a condenser or Leyden jar, owing to the fact that the inner and outer masses of metal which constitute the primary and secondary windings are separated by a thin layer or layers of dielectric material, so that they act like the plates of a condenser. This action interferes to some extent with the proper operation of the coil, and it has been found that a beneficial result is obtained by interconnecting the primary winding and the grounded terminal of the secondarv winding. Such connection iS objectionable, however, where it is desired to employ'` ajcompletcly insulated primary circuit. 5A feature of the present invention resides-in the means for preventing an accumulation of static charges in the primary and secondary windings without grounding the primary circuit. This is accomplished, as hereinbefore stated, by employing a connection between the primary and secondary windings which is interrupted by a slight air-gap. As shown in Fig. 2, this is arranged by providing one of the primary binding-posts 35 with a projecting point 40 which nearly, but not quite, touches the nut 21 on the tie-rod. It will be seen that except for the air-gap between the point and the nut a short conductive path of low resistance is afforded between the primary and secondary windings by way of the point 40, the tierod, the core, the pin 38 and the strip 37, and in this manner static charges are prevented from accumulating except to the slight extent necessary to produce a discharge across the air-gap. y

When a constant flow of current is produced through the primary winding 19 the heat generated in this winding is freely dissipated by radiation and convection, and since the casing 24 may be made of metal or other material having'liigh heat-conductivity, it aliords little obstruction to the dissipation of this heat. Accordingly, the primary winding is prevented from attaining a Copies of this patent may be obtained for dangerous temperature, while the intervening insulating-material very eliectually protects the secondary ywinding from the heat. The coil will, therefore, endure a continuous heavy flow of current without damage, and

the use of a resistance-device or an automatic cut-out is unnecessary, in so far as protection of the coil is concerned.

The invention is not limited to the embodiment thereof hereinbefore described and illustrated in the accompanying drawings, but it may be embodied in various other forms within the scope of the following claims.

The invention claimed is:

1. An ignition-coil comprising a substantially closed core; a high-tension secondary winding nupon the core; a low-tension primary winding arranged outside the secondary windi'ng: a jacket of insulating-material, between the said windings, spacing them apart and provided with a slot extending longitudinally; and an insulated yconductor extending, from the outer terminal of the secondary winding, outwardly through said slot. l

2. An ignition-coil comprising a primary winding; a high-tension secondary winding; and a connection, between the primary winding and one terminal of the secondary winding, of a resistance high enough to prevent substantial flow of primary current but low enough to permit the discharge of static charges between the two windings.

3. An ignition-coil comprising a primary winding; a high-tension secondary winding; and a connection, between the primary winding and one terminal of the secondary wind-v ing, of high non-inductive resistance.

4. An ignition-coil comprising a primary winding; a high-tension secondary windin and a connection, between the primary wining and one terminal of the secondary winding, including an air-gap short enough to permit the discharge, through said connection, of static charges between the said windings. n

5. An ignition-coil having, in combination, a core of iron wires; a winding thereon; a strip of sheet-metal connected with a terminal of said winding and lying over an end of said core; and a pin driven through said sheet-metal and between the wires of the core.

.EARLE P.y LEE.

ve cents each, by addressing the Commissioner of Patents, Washington, D. C. 

